A fast neutron dosimeter is proposed which would be used by personnel involved in research or medical treatment with neutrons, and thus satisfy some of the needs of the National Cancer Institute. The dosimeter proposed herein is sensitive (from first principles) to neutrons of >3 keV energy with negligible responses to other radiation. The novel system uses resonance ionization spectroscopy (RIS) to count noble gas atoms sputtered from a solid matrix material by collision events that correlate with neutron dose. The solid matrix material and the noble gas atoms released from it would be contained in the "neutron badge"; the noble gas atoms released during the exposure period would then be counted in a laboratory "reader" using RIS. The ultra-high sensitivity and selectivity of RIS allows reliable determination of the small number of atoms released. Calculations indicate sensitivity below 1 mrem, and NCRP 39 rem response constant within a factor of two to neutrons from 3 keV to 20 MeV. Phase I would investigate feasibility by experimentally verifying that noble gas atoms are released from the solid matrix by neutron irradiation, and that the spontaneous release of noble base atoms from the matrix can be reduced to acceptable levels. Phase II will require sensitivity and energy response measurements, development of low-background packaging and practical readers, and field tests of prototype units in mixed radiation environments.